Online NMR FID Processor & Spectra Analyzer Free • In-Browser
Interactive tool for converting Free Induction Decay (FID) files into high-resolution 1H, 13C, and 2D NMR spectra (COSY, HSQC, HMBC) with zero software installation.
fid, or JCAMP (.dx)Understanding Free Induction Decay (FID) and NMR Signal Processing
In Nuclear Magnetic Resonance (NMR) spectroscopy, Free Induction Decay (FID) is the observable, time-dependent electromagnetic signal produced by the macroscopic transverse nuclear magnetization precessing around the static magnetic field (B0) after a radiofrequency (RF) excitation pulse. Because the raw FID recorded by spectrometer receivers exists in the time domain [S(t)], it appears as an exponentially decaying sinusoidal wave comprising overlapping frequencies from every distinct chemical environment in the sample.
To extract chemical shifts (δ in ppm) and spin-spin coupling constants (J in Hz), the time-domain signal must undergo mathematical transformation and spectral conditioning:
1. Apodization & Zero Filling
Multiplying the raw FID by mathematical window functions (Exponential multiplication for sensitivity enhancement or Lorentzian-to-Gaussian transformation for peak resolution). Zero-filling doubles the dataset size with zeros before transformation to improve digital resolution.
2. Fourier Transformation (FT)
The mathematical operation converting time-domain data [S(t)] into a frequency-domain spectrum [S(ν)]. This resolves individual nuclear resonance frequencies corresponding to distinct chemical environments.
3. Phase & Baseline Correction
Correcting zero-order (φ0) and first-order (φ1) phase errors caused by receiver delay and filter dispersion to produce pure Lorentzian absorption peak shapes, followed by polynomial baseline flattening.
Common Deuterated NMR Solvents: Residual Chemical Shift Reference
Accurate calibration of chemical shifts (δ) depends on referencing the residual non-deuterated solvent peak. Below is a quick diagnostic guide for common deuterated solvents in 1H-NMR and 13C-NMR spectroscopy:
| Solvent Formula | Name | Residual 1H Shift (δ ppm) | 1H Multiplicity | 13C Central Shift (δ ppm) | 13C Multiplicity |
|---|---|---|---|---|---|
| CDCl3 | Deuterated Chloroform | 7.26 | Singlet (s) | 77.16 | Triplet (1:1:1) |
| DMSO-d6 | Hexadeuterodimethyl sulfoxide | 2.50 | Quintet (quint) | 39.52 | Septet (1:2:3:4:3:2:1) |
| CD3OD | Tetradeuteromethanol | 3.31 (CH3), 4.87 (OH) | Quintet / Singlet | 49.00 | Septet |
| (CD3)2CO | Acetone-d6 | 2.05 | Quintet | 29.84, 206.26 | Septet, Singlet |
| D2O | Deuterium Oxide | 4.79 | Singlet (broad) | — | — |
| C6D6 | Deuterated Benzene | 7.16 | Singlet (broad) | 128.06 | Triplet |
| CD3CN | Acetonitrile-d3 | 1.94 | Quintet | 1.32, 118.26 | Septet, Singlet |
Supported File Formats & Spectrometer Architectures
Bruker TopSpin / XWIN-NMR
Drag the entire numbered acquisition folder (e.g. 1/, 10/) containing fid, acqus, acqu2s, and pdata/, or drag a .zip file of the experiment folder.
JCAMP-DX Standard
Fully compliant with IUPAC JCAMP-DX standard files (.dx, .jdx). Both time-domain and pre-transformed frequency spectra are parsed instantly.
Varian / Agilent & JEOL
Supports Varian fid alongside procpar parameter files and JEOL Delta format single files.
Chemical Structure Correlation (.mol)
Import MOL structures or paste SMILES strings to assign protons and carbons directly to peaks for multiplet verification.
Frequently Asked Questions (FAQ)
Why does dragging only the ‘fid’ file sometimes fail for Bruker data?
A raw Bruker fid file contains only raw binary digitized data points. The spectrometer frequency (SFO1), spectral width (SW), nucleus type, and acquisition parameters are stored separately in the acqus file. Always drag either the entire experiment folder or a ZIP file containing both fid and acqus so the processor knows the correct magnetic field parameters.
How can I export publication-ready NMR figures for research papers?
Once your spectrum is phased, baseline-corrected, and integrated, click the Export icon in the right-hand panel. You can download vector-quality SVG (ideal for Adobe Illustrator, ChemDraw, or Inkscape), print-ready PDF, or high-DPI PNG images.
Can I process 2D NMR experiments like COSY, HSQC, and HMBC?
Yes. The processor handles 2D matrix transformation in both F1 and F2 dimensions, including homonuclear experiments (COSY, TOCSY, NOESY) and heteronuclear correlations (1H-13C HSQC, 1H-13C HMBC). You can adjust contour levels directly with mouse wheel scrolling.